Sulphurized oils



Patented Aug. 29, 1944 SULPHURIZED OILS Bert H. Lincoln and Waldo L. Steiner, Ponca City, i kla., assignors to Continental Oil Company, Ponca City, Okla., a corporation oi Delaware No Drawing. Application January 4, 1940,. Serial No. 312,408

-' 2 Claims.

This invention relates to sulphurized oils and new compositions of matter used in the preparation thereof and is a continuation-in-part of our co-pending application, Serial No. 257,458, filed February 20, 1939, issued January 4, 1940, as Patent No. 2,186,646. It has long been known that sulphur compounds, when added to lubricating oils, impart certain properties to the mixtures which are of great value when these mixtures are used as lub'ricants for very heavy duty such as is encountered in the lubrication of automotive gears of the hypoid and spiral bevel types and other power transmission gears and for the lubrication of cuttingtools such as are used in cutting and threading steel pipe. The exact manner in which the sulphur compounds, with respect to the .cutting lubricants, act to produce these results is not known with any degree of certainty; It is more than a matter of the increased film strength.

which sulphur compounds impart to lubricatin oils, since, for each sulphur compound that may be added to a lubricating oil to increase its film strength, there is an optimum percentage above which there is no tendency to obtain further increase with greater percentages of the sulphur compound. On the other'hand, there seems to be no limit to the improvement or a cutting oil that can be obtained by increasing its sulphur content, at least asfar as the smoothness of the metal cut obtained with it is concerned.

All sulphur compounds do not have this beneficial effect on lubricants to the same degree for the same amount of sulphur, as will be brought out in the examples given hereinbelow; and to most of those now in use, there are certain definite objections. The most common sulphur compounds used for blending with lubricating oils are the .sulphuretted glycerides of the unsaturated fatty acids. These usually contain about 12 per cent sulphur. Sulphuretted lard oil is a typical example. .These compounds are not entirely satisfactory for blending purposes for several reasons. The sulphuretted glycerides are very viscous and hard to handle and raise the pour point of the oil with-which they are blended, have a very strong odor of hydrogen sulphide, are irritating to the skin of the operators working with them, are not as stable as desired when in use and do not give a good cut when used in a cutting lubricant, do not give a very high film strength when used in an extreme pressure lubricant, are not entirely oil soluble, and are not refinable to any extent.

Even with using a large percentage of these sulphur-base oils, cutting lubricants are obtained which are rather in'efllcient as far as cutting qualities are concerned, objectionable on account of odor, irritating to the skin of the operator and in case of slight cuts on the hand cause sores diflicult to heal, are very viscous when cold, are not stable to high temperatures while in use, and

. break down and release Has.

' An extreme pressure lubricant for gears which is made from the conventional sulphuretted glycerides, such as lard oil, has many defects. In the first place, this type of sulphur-base blend is not as stable as is desired to the copper stripcorrosion test, which some automobile manufacturers now require for sulphur-base lubricants. Secondly, the film, strength is not very high; andlast, the pour point of the lubricant is raised five degrees to 25 degrees F., depending upon the type of petroleum base oil used.

We have discovered that the sulphuretted or sulphurized synthetic monohydric and dihydric alcohol esters of, organic acids make excellent sulphur bases for blending with lubricants forpreparing superior cutting oils and gear lubricants. By the term sulphur we mean the introduction or sulphur in the form in which it is introduced into a synthetic ester by means of sulphur or a halide of sulphur. These compounds are superior to the conventional sulphuretted glycerides oi. unsaturated fatty acids in a number of ways. To begin with, they are in general much less viscous even when containing a much larger percentage of sulphur and are therefore easier to handle. They may be easily and permanently freed from the odor of hydrogen sulphide by blowing for a few minutes with sulphur dioxide after sulphurettlng, followed by an inert gas such as carbon dioxide. They are, as a group, much more stable to heat than the sulphuretted glycerides and consequently do not break down and release H28 in service as readily. When'the glyceride breaks down, glycerine is released which forms gum and is generally objectionable.

When used in a cutting oil, they do not irritate the skin of the operators. They are cheaper because about twice as much sulphur may, be added to this type of compound as can be added to the glycerides, and thus they give a more concentrated base, Another important advantage of these sulphuretted or sulphurized synthetic monohydric and dihydric alcohol esters is that they are more soluble in petroleum lubricants I tainer in which a blend of this type base and a petroleum lubricant has stood for some time. The reason for this phenomenon is that glycerides tend to polymerize on sulphuretting and form oil insoluble polymers, whereas their corresponding synthetic monohydrie esters show little or no tendencs to polymerize on sulphui'etting Olf sulphu'risingt. The pour point of blends made with a peti'o eum lubricant is higher by 13 to 25 F. (de'pen g on the type of lubricant) when a suiphuretted glycericle is used than when the corresponding sulphuretted or sulolcusizecl synr tioh'yclrlc alcohol ester is used. The lateffect the emulsion characteristics and e sluclee formins tendencies of the which they ate blended. The sulweal l, ycericles cause emulsion trouble anal ver much higher for the same amount siuoliur temperatures from 1 degrees ees than similar blends where the sulohuretted, or sulphurizecl synthetic monohveric alcohol esters of the same acids are used. This is c. very important factor when considering either a cutting oil or a power transmission gear lubricant. In the case oi the former, it is frequently clifiicult to obtain as good flow of the cutting oil from the sump of the machines on cold inc-mines in a shop that is not too Well heated. Under these conditions, the machines do poor work; and the cutting tools are dulled. The disadvantages ofa high pour test aml high viscosity at cold weather temperatures in the case of gear lubricants cause excess loss of power in overcoming the internal friction of the lubri cent and clifficulty in Shifting of gears in the case of automobile transmission gears.

We have found more particularly thatcerteln synthetic esters of mono and dihyclrie phenols with organic acids are especially suited. tosulphurization and use when blended in t'oineral oils for lubricating purposes. The mono and clihyclric phenols which we may use may be monoor bipolycyclic and may contain various substltuents and/or side chains in addition to the one or two hydroxyl groups. The organic acids which we may use to esterlfy with suclo phenols are of various types, including the acids (free or combined) occurring in natural fats, waxes, and. saponiflable oils, as well as synthetic eciels. Oi these acids, however, we prefer the unsaturated ones because their esters are easier to sulphurize than thesaturatecl ones. The latter may be satisfactorily used if higher temperatures and longer times of .sulphuriziug are employed as describes? below.

Some examples of the esters We may sulphux'ize are given below, and it is to be understood that any of the phenolic components mentioned may be combined with eny'of the acid radicals men-- tioned to obtain further examples of the esters we may sulphurize. It is also to be understood that the following esters, when sulphurizerl and blended with mineral oil, are to be considered as examples of our invention: 3

'Phenyl einnamate Phenol esters of com oil acirls Fhenyl mellisate Hyclroouluoue distearate Resotcinol esters (oil of soy been oil acids Cateol'icl esters (d1) of Wool fat acids Foeuyi oleate eellaplithyl liuolecte b-Nepfothyl liuoleate Ester of B-hydroxyquinoline with beeswax acids Phenyl esters of sperm oil acids Anthryl oleate Cresvl abieta'w Phenolic esters of the acids of naturally occurring wanes such as camaul'za, candelille, someone, Japan, montan, one best-ester Phem l llnoleate.

Neturally occurring oils Waxes so such containing monohydrie alcohol ester of organic acids have proved unsatisfactory lnveotlon. The reason for up"; these uatumlly occurring subst ture of esters with naturally occ such as e'l'ycericles, high mo hols, .l'rrclrocarcons, often '11 and other impurities. I. in; this grougo ere sperm oil 5 per cent to 25 per cent of glycer o it unsatisfactcr It also cont which ore objectionable, since they also give E3153" tively unstable derivatives on sulrtm zinu removal of the monohyclric or uilizruiic alcohol esters as such from theiglycericles, iree alcohol, and other impui'lties in the naturally oec materiel is not commercially fees When sperm oil is sulphurlzerl, c product tainecl which does not lend itself to r ters; consequently it cannot be used in a emote ease lubricant as on oiliness and film strength improves or as a sludge inhibitor because oi adverse ellect on color, emulsibility, cull clouzl test. The objectionable characteristics of the sly-- cerides as desctlbecl previously are in general 9 pestineut to the sulphuz'ized naturally occurringesters with only a few exceptions.

Wool fat or wool grease contains monohydflo alcohol esters: but is not satisfactom' for use in our invention because of naturally occurring 1:..- purltles found therein. These consist of elkell salts of fatty acids and free high molecular weight alcohols which yield relatively unstable sulphur flerivatives. Sulphurized W001 fat is not 2. satls= factory lubricating oil addition agent because it is not stable enough to allow refining; and when curled to mineral oils, the resultant blend will not give a satisfactory emulsion or cloucl test. 8111 phurlzecl wool fat darkens the color of the oil. it also breaks down at relatively low temperatures compared with sulphurized synthetic esters) anal releases Has, which is objectionable. Hence Wool fat would not give a. satisfactory lubricating oil addition agent after sulphurizing.

Beeswax contains 19 to 20 per cent free fatty acid and to per cent hydrocarbons i therefore unsuited for the production of a sun phurized addition agent for lubricating oils.

Canoleiille wax contains, besides uzounliy'clrlc alcohol esters, about 10 per cent or more free fatty acid and about per cent hydrocarbons. Cor nauba wax contains some monohydric alcohol c ters, but these are mixed with a complex variety of impurities such as free fatty acids, hydrccor bons, and free high molecular weight alcohols; and therefore neither candelilla nor carnauba wax is suitable for 'use' as lubricating oil addition agents after being sulphurizerl.

However, the above-mentioned materials, namely naturally occurring wax containing so poniflable oils, sperm oil and slmilar'whale oils,

compounds to obtain products with active sulphur.

2. Proportiohs of recounts-For the preparation of products with active sulphur, we prefer to use large roportions of sulphur or sulphur compounds because it is easier to obtain the desired product, other factors being constant. It is possible, however, at lower temperature and with shorter periods of heating especially in solvents, to obtain active sulphur pontaining products using small amounts o1 tlon but only by the appended claims interpreted as broadly as the prior art permits.

The sulphurization of our .phenolic esters may be accomplished by heating the synthetic esterwith sulphur or a halide of sulphur in the pres ence or absence of a solvent. The temperature used depends on the particular synthetic ester. About 350 to 380 F. is used on esters derived from unsaturated vacids and about 380 to 450 F. is necessary for esters derived from saturated acids. initial boiling points of 350 F. and higher may be used up to such light lubricating oils as a neutral oil having a viscosity of 150 S. S. U. at

As solvents, petroleum fractions having sulphur. By controlling reagents and conditions we are able to obtain sulphur bearing derivatives with 2 to 20 per cent or more sulphur. For any given sulphur content, we may obtain products containing active sulphur or containing only inactive sulphur.

3.-'Temperature.-Higher temperatures I tend to fix the sulphur in inactive combination and are used when a .stable sulphurized synthetic ester is desired. Use of lower temperatures with the same reagents and otherwise the same conditions gives products containing active sulphur 100 F. The more volatile solvents of this type may be removed by distillation with steam or in a vacuum while the higher boiling neutral oils may be left in the sulphurized ester if they are taken into consideration when subsequent blends are made.

In sulphurizing our phenolic esters we may use f elemental sulphur or various compounds of sulphur including sulphur monochloride, sulphur dichloride, phosphorus pentasulphide, phosphorus trisulphide, polysulphides, and the like. Each of these reagents gives somewhat different products. Furthermore, by variations in the conditions of sulphurization, we may obtain two general types of products from each reagent regardless of sulphur content. One of these contains some active sulphur, and the other contains no active sulphur; that is, all the sulphur is in an inactive form. By active sulphur we mean that form which is present when a blend of the sulphurized material in 150 neutral oil containing one per cent of added sulphur will appreciably discolor a bright copper strip immersed therein and held'at 210"" F. for 30 minutes. If the copper strip is not appreciably discolored, all the sulphur present is in an inactive form.

Both types of sulphurized products are useful for difierent purposes. containing active sulphur are more effective components of gear lubricants and the like where extreme pressure is used and no easily corrodible metals are present. For crankcase use, however, especially where bearing metals sensitive to corrosion are employed, our product con taining only inactive sulphur is preferred.

Various factors must be considered in the preparation of our sulphurized phenolic esters containing active and inactive sulphur:

l. Reagent-In general for the preparation of sulphurized phenolic esters containing active sulphur, we prefer to use elemental sulphur combined with short times of heating and lower temperatures. The sulphur compounds such as chlorides of sulphur andsulphides of phosphorus are more likely to give products contai ning only inactive sulphur and are, not so flexible with For example, materials,

which are especially useful forcutting oils and extreme pressure gear lubricants when blended with hydrocarbon oils and other ingredients.

4. Time -We heat our reactants fora relatively short time to produce materials with active sulphur and for a relatively long time to obtain only inactive sulphur in our products. A short time at a high temperature may be selected which is the equivalent of a longer time at a lower-temperature within certain limits.

There is, however, a most suitable range of temperaturebelow which the time required is unreasonably long.

5. 'Soluents.-Insert solvents may be employed; and, in general, they have the eflectof limiting the highest temperature used in a particular sulphurization. If the solvent does not dissolve the sulphur or sulphur compound appreciably, the rate of reaction is slower and the formation of products containing active sulphur is favored. If the solvent dissolves the sulphur or sulphur compound, the reaction proceeds more rapidly; and products containing only inactive sulphur are more readily obtained.

6. Unrefined products are more likely to contain active sulphur than unrefined products. We vary the quantities of refining reagents, for example, sulphuric acid and clay, and also their concentration, time, and temperature of contact, etc., to obtain thorough refining when a very stable product is desired. The refining may be milder or even omitted when an active sulphur product is sought.

. 7. Pressure.-Under superatmoslpheric pressure the sulphur is more stably fixed in the same time and under the otherwise same conditions,

and this is a useful modification of our process in order to obtain products containing only inactive sulphur.

While there is no specific limits. on to the amount of added sulphur in the form of sulphurized phenolic esters that should be used in preparing diilerent lubricants, usually 1 to 4 per cent or more may be used for cutting oils; and about .5 to 2.5 .per cent or more will usually be sufilcient for gear and other extreme pressure lubricants. As little as .001 per cent or a little less and up to .25 per cent or more may be used in oils for use in automobile crankcases.

or larger quantities may be used in any case with results which are partially satisfactory. They are given because generally speaking the optimum results can be obtained by using the ratios within the limits that are suggested.

The hydrocarbon oils which are used in blending with the sulphurized phenolic esters are not limited to the hydrocarbon oils cited in the examples but are to include any oil of any type or viscosity such as may be required by the lubricant in question. These different types of oils may be unrefined mineral oil or oil refined by any method, such as by the use of acids, alkalis, or solvents. or any combination of said refining processes. othertyp s are synthetic oils made by polymerization or similar processes and hydrogenated oils. I

Sulphur dioxide and carbon dioxide have been mentioned as agents for blowing sulphurized synthetic esters and it is to he understood that the inventors are in no way limited to any particular refining process and that other gaseous or liquid refining agents as nitrogen or alkali solutions and acid solutions may be used in refining sulphurized phenolic esters of certain character and for certain purposes.

Having thus described our invention, we claim:

1. A lubricant comprising in combination a major amount of a lubricating oil and a minor amount of a sulphurized ester of henol and an unsaturated organic acid, said ester being sulphurized by a compound containing phosphorus and sulphur.

2. A lubricant comprising in combination a major amount of a lubricating oil and a minor amount of a sulphurized ester of phenol and an unsaturated organic acid, said ester being sulphurized by phosporus pentasulphide.

' BERT H. LINCOLN.

WALDO L. STEINER. 

